The present invention relates to a method for processing photosensitive copying materials and in particular to a method for processing photosensitive copying materials which can reduce the amount of a developer used and is favorable for environmental protection.
There have been known, for instance, presensitized plates for use in making lithographic printing plates (hereinafter referred to as "PS plates"), photosensitive resist materials and photosensitive proofing materials as photosensitive copying materials which comprise photosensitive components such as o-quinonediazide compounds, diazonium salts, photopolymerizable photosensitive materials or photocrosslinkable photosensitive materials.
In particular, a positive-working PS plate which has been widely used comprises an aluminum plate serving as a support provided thereon with a photosensitive layer comprising an o-quinonediazide compound. It has been known that the o-quinonediazide compound is converted into a carboxylic acid through the irradiation with ultraviolet rays and accordingly if an exposed PS plate is developed with an aqueous alkaline solution, only the area on the photosensitive layer exposed to light is removed to expose the support surface. Since the surface of the aluminum support is hydrophilic, the surface (non-image area) of the support exposed through the development retains water and repels a printing ink. On the other hand, the area (image area) from which the photosensitive layer is not removed through the development is lipophilic. Therefore, the image area repels water and receives a printing ink.
There have been known various kinds of aqueous alkaline solutions used as developers for such positive-working PS plates and most preferred are aqueous solutions of silicates such as sodium silicate and potassium silicate. This is because the developing ability thereof can be controlled to some extent by adjusting the ratio of silicon oxide to alkali metal oxide (in general expressed in terms of a molar ratio [SiO.sub.2 ]/[M.sub.2 O]), which are components of the silicate, and the concentration of the silicate.
Besides the foregoing positive-working PS plates, these silicates have preferably been used as components of the developers for reversal negative-working PS plates which are provided with o-quinonediazide photosensitive layers as disclosed in Japanese Patent Publication for Opposition Purpose (hereinafter referred to as "J.P. KOKOKU") No. Sho 56-14970 and negative-working PS plates which are provided with photosensitive layers comprising resins carrying dimethylmaleimido groups on the side chains as photocrosslinking agents.
As has been discussed above, the usual development of these photosensitive copying materials comprises dissolving the area on the photosensitive layer corresponding to non-image portions with a developer to thus reveal the support surface. For this reason, the concentration of the photosensitive components dissolved in the developer gradually increases as the development proceeds and this results in the formation of dregs and sludge and a reduction of the processing ability (ability of dissolution) of the developer.
Moreover, automatic developing machines for PS plates have widely been employed in the field of the plate-making and printing to rationalize and standardize the plate-making operations. The automatic developing machine in general comprises a device for conveying a PS plate to be processed, a bath for accommodating a developer and a device for spraying the developer and developing the PS plate by pumping up the developer and spraying it on the exposed PS plate through a spray nozzle while horizontally conveying the exposed PS plate. Alternatively, there has also been known a method which comprises conveying an exposed PS plate while immersing the plate in a developer contained in a developing bath by the action of submerged guide rolls.
When positive-working PS plates are processed using such an automatic developing machine and a large amount of the PS plates are processed, the method suffers from problems of formation of insoluble dregs and sludge and clogging of a spray pipe and a nozzle.
There have been proposed techniques for eliminating these drawbacks, for instance, methods for maintaining the processing ability of a developer and hence preventing the formation of dregs and sludge through supplementation of a replenisher (see, for instance, Japanese Unexamined Patent Publication (hereinafter referred to as "J.P. KOKAI") No. Sho 54-62004(=U.S. Pat. No. 4,259,434) and J.P. KOKOKU No. Sho 57-7427(=U.S. Pat. No, 4,259, 434). These methods make it possible to eliminate the formation of such insolubles, but are accompanied by an increase in waste liquor. This problem can be solved by the method disclosed in J.P. KOKAI No. Hei 2-3065(=EP 347245A), but it has still been requested to reduce the running cost and the amount of the waste liquor. In particular, the reduction in the industrial waste has attracted special interest recently on a worldwide scale.
On the other hand, representative negative-working photosensitive copying materials include PS plates provided with photosensitive layers comprising diazonium salts. In addition, there have recently been known, for instance, negative-working PS plates having photosensitive layers which comprise polymerizable monomers and photopolymerization initiators and those having photocrosslinkable photosensitive layers which comprise, for instance, cinnamic acid and dimethylmaleimides.
In the development of these negative-working PS plates, there is a limit in the processing ability of the developer like the foregoing positive-working PS plate and a large amount of replenisher must be employed. Moreover, the processing of a large number of PS plates is accompanied by deposition of dregs and sludge due to the components of the photosensitive layers and accordingly it is difficult to perform stable processing over a long time.
Besides, J.P. KOKOKU Nos. Sho 54-21089(=U.S. Pat. No. 4,207,106) and Sho 37-11558(=U.S. Pat. No. 3,136,637) disclose multi-layer photosensitive copying materials comprising organic coating layers hardly soluble in developers applied onto photosensitive layer comprising o-quinonediazide compounds or photosensitive diazo resins. These photosensitive copying materials are preferred for the reasons that they contain only a small amount of the components soluble in the developers and accordingly the developer is deteriorated by the processing only to a small extent. However, these photosensitive layers and polymeric compounds useful as the organic coating layers have many common solvents and thus the polymeric compounds usable as the organic coating materials are limited to those soluble in poor solvents for the components of the photosensitive layers. Furthermore, the dregs of the organic coating layer which are scraped out in the developer and get swollen is again deposited on the processed PS plates and those during processing and are precipitated in the developer. This makes stable processing over a long time impossible.